Christmas is coming early — and the network, home to young adult gibberish “Haven” and “Bitten,” ultra-cheap “Killjoys” and just pure dreck “Sharknado” — knows it has to reward the adults left standing in the room if it wants to stay on Santa’s good side.

Of course, what “Childhood’s End” — the miniseries running tonight through Wednesday at 8 p.m. — and “The Expanse” have in common is that they are both adaptations of somber, best-­selling science fiction novels.

“The Expanse,” based on the series of books by the same name by Daniel Abraham and Ty Franck (under the pen name James S.A. Corey), just might be a worthy successor to the network’s much beloved “Battlestar Galactica.”

Two hundred years from now, humanity has spread out across the stars.

Mars is an independent military power, on the brink of war with Earth.

On the colonies in-between, the residents — “belters” — value air and water more than gold, we’re told.

Life is treacherous there. One miner working in space loses an arm when a shipment of ice crashes into him.

Holden (Steven Strait, “Magic City”) is the second officer on a broken-down ice-freighter and happy sliding under the radar.

Then the first officer (Jonathan Banks, “Better Call Saul,” in a terrific cameo) suffers a psychotic break.

“We make it all this way, so far out into the darkness ­— why couldn’t we have brought more light?”

Suddenly Holden gets a promotion he wants as much as a lobotomy.

“Evolve or die,” his captain tells him.

That theory will be put to the test sooner than anyone could predict.

The ship receives a distress signal. The captain and most of the crew would just as well keep to their schedule so they can receive their company bo­nuses, but Holden can’t get it out of his mind.

He gathers a small crew and takes a shuttle to investigate.

They find what appears to be a ghost ship. There’s a hole in its side — but no bodies.

Then things really get bad.

Meanwhile, on one of the colonies, Josephus Miller (Thomas Jane, “Hung”), a jaded detective, gets roped into a missing persons case.

And on Earth, Chrisjen Avasarala (Emmy winner and Oscar nominee Shohreh Aghdashloo, “House of Sand and Fog”), the head of a political dynasty, interrogates an off-worlder.

What does it all mean? What ties it all together?

Nothing less than the greatest conspiracy of the universe.

“Expanse’s” look is typical Syfy. The lighting is used to bathe the sets in shadows to hide the lack of money in the budget. The cast and the sheer complexity and depth of story, however, are worthy of premium cable.

The series has a first season order of 10 episodes (an additional hour airs tomorrow at 10 p.m.). I have a feeling that won’t be enough.